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a-simple-shaping-example.html
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a-simple-shaping-example.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<title>A simple shaping example: HarfBuzz Manual</title>
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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="a-simple-shaping-example"></a>A simple shaping example</h2></div></div></div>
<p>
Below is the simplest HarfBuzz shaping example possible.
</p>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>
Create a buffer and put your text in it.
</p></li></ol></div>
<pre class="programlisting">
#include <hb.h>
hb_buffer_t *buf;
buf = hb_buffer_create();
hb_buffer_add_utf8(buf, text, -1, 0, -1);
</pre>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem" value="2"><p>
Set the script, language and direction of the buffer.
</p></li></ol></div>
<pre class="programlisting">
// If you know the direction, script, and language
hb_buffer_set_direction(buf, HB_DIRECTION_LTR);
hb_buffer_set_script(buf, HB_SCRIPT_LATIN);
hb_buffer_set_language(buf, hb_language_from_string("en", -1));
// If you don't know the direction, script, and language
hb_buffer_guess_segment_properties(buffer);
</pre>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem" value="3"><p>
Create a face and a font from a font file.
</p></li></ol></div>
<pre class="programlisting">
hb_blob_t *blob = hb_blob_create_from_file(filename); /* or hb_blob_create_from_file_or_fail() */
hb_face_t *face = hb_face_create(blob, 0);
hb_font_t *font = hb_font_create(face);
</pre>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem" value="4"><p>
Shape!
</p></li></ol></div>
<pre class="programlisting">
hb_shape(font, buf, NULL, 0);
</pre>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem" value="5"><p>
Get the glyph and position information.
</p></li></ol></div>
<pre class="programlisting">
unsigned int glyph_count;
hb_glyph_info_t *glyph_info = hb_buffer_get_glyph_infos(buf, &glyph_count);
hb_glyph_position_t *glyph_pos = hb_buffer_get_glyph_positions(buf, &glyph_count);
</pre>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem" value="6"><p>
Iterate over each glyph.
</p></li></ol></div>
<pre class="programlisting">
hb_position_t cursor_x = 0;
hb_position_t cursor_y = 0;
for (unsigned int i = 0; i < glyph_count; i++) {
hb_codepoint_t glyphid = glyph_info[i].codepoint;
hb_position_t x_offset = glyph_pos[i].x_offset;
hb_position_t y_offset = glyph_pos[i].y_offset;
hb_position_t x_advance = glyph_pos[i].x_advance;
hb_position_t y_advance = glyph_pos[i].y_advance;
/* draw_glyph(glyphid, cursor_x + x_offset, cursor_y + y_offset); */
cursor_x += x_advance;
cursor_y += y_advance;
}
</pre>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem" value="7"><p>
Tidy up.
</p></li></ol></div>
<pre class="programlisting">
hb_buffer_destroy(buf);
hb_font_destroy(font);
hb_face_destroy(face);
hb_blob_destroy(blob);
</pre>
<p>
This example shows enough to get us started using HarfBuzz. In
the sections that follow, we will use the remainder of
HarfBuzz's API to refine and extend the example and improve its
text-shaping capabilities.
</p>
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